#ifndef _VECTOR_H
#define _VECTOR_H

#include <math.h>

struct vector {
	double x;
	double y;
};

/*
 * res = a - b
 */
static inline void vector_sub(const struct vector *a, const struct vector *b,
		struct vector *res)
{
	res->x = a->x - b->x;
	res->y = a->y - b->y;
}

/*
 * res = a + b
 */
static inline void vector_add(const struct vector *a, const struct vector *b,
		struct vector *res)
{
	res->x = a->x + b->x;
	res->y = a->y + b->y;
}

static inline double vector_abs(const struct vector *a)
{
	return sqrt(a->x * a->x + a->y * a->y);
}

static inline void vector_scale(const struct vector *a, const double b,
				struct vector *res)
{
	res->x = a->x * b;
	res->y = a->y * b;
}

static inline void vector_div(const struct vector *a, const double b,
			      struct vector *res)
{
	res->x = a->x / b;
	res->y = a->y / b;
}

#endif